1. Field
Embodiments generally relate to an organic light emitting diode (OLED) display, and more particularly, to a transparent organic light emitting diode display.
2. Description of the Related Art
An organic light emitting diode display includes a plurality of organic light emitting diodes, each diode having a hole injection electrode, an organic emission layer, and an electron injection electrode. Holes supplied from the hole injection electrode, e.g., anode, and electrons supplied from the electron injection electrode, e.g., cathode, may be recombined as an exciton, i.e., an electron-hole pair, in the organic emission layer. The organic emission layer may emit light when the exciton returns to a base energy state, e.g., exciton drops from an excited state to a ground state. Organic light emitting diode displays may display an image using this light emission.
Based on such principle, the organic light emitting diode display has a self-luminous characteristic, and because the organic light emitting diode display does not need a light source, unlike a liquid crystal display, it can have a relatively small thickness and weight. Further, organic light emitting diode displays generally have a variety of beneficial properties such as low power consumption, high luminance, quick response time, etc. Therefore, the organic light emitting diode displays may be used as an alternative display for portable electronic devices.
In addition, in view of its characteristics, organic light emitting diode displays may be made as a transparent display device that enable a user to see an object or image located on an opposite side with the object or image being projected through the organic light emitting diode display. That is, the organic light emitting diode display can be manufactured such that, when it is in an off state, an object or image located at the opposite side may be projected, and when the organic light emitting diode display is in an on state, an image emitted from the organic light emitting diode display can be seen.
However, when the organic light emitting diode display is in the off state, the object or image located at the opposite side may be projected through a space between patterns, such as a thin film transistor and various wiring, as well as through the organic light emitting diode display, before being transferred to the user. Typically, a gap between the patterns is about several hundreds of nm, and has the same level as the wavelength of light in a visible region, thus causing scattering of transmitted light. Thus, the image transferred to the user may be a distorted image.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the described technology and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.